Rotary table

ABSTRACT

A free-wheeling rotary table comprising a base member, a horizontally disposed rotatable table member adapted to support an object for rotation about a generally vertical rotational axis, antifriction bearing means on one of the members arranged generally coaxially of the rotational axis, and a bearing surface on the other of the members engageable with the bearing means and defined at least in part by an imaginary sphere having its center located along the rotational axis of the table member.

I United States Patent [151 3,653,340 Bugg Apr. 4, 197 2 54] ROTARYTABLE FOREIGN PATENTS OR APPLICATIONS [7 21 Inventor: Charl H- B gg, M nl n Mi h- 1,011,884 12/1965 Great Britain 108/1 39 [73] Assignee:Machine Products Corporation, Detroit, I

Mich Primary Exammer.lames C. Mitchell Attorney-Harness, Dickey & Pierce[22] Filed: July 1, 1970 [2]] App]. No.: 51,598 ABSTRACT A free-wheelingrotary table comprising a base member, a [52] US. Cl ..l08/l39, 108/103,248/425 horizontally disposed rotatable table member adapted to sup- [51Int. Cl. ..A47b 11/00 port an object for rotation about a generallyvertical rotational [58] Field f Search 9, axis, antifr'iction bearingmeans on one of the members ar- 248/425 ranged generally coaxially ofthe rotational axis, and a bearing surface on the other of the membersengageable with the bear- [56] References cued ing means and defined atleast in part by an imaginary sphere UNITED STATES PATENTS having itscenter located along the rotational axis of the table member. 875,49412/1907 Bedell ..l08/l39 X 3,063,714 1 l/l 962 Krauss ..l08/l 39 X 8Claims, 4 Drawing Figures PATENTEDAPR 4 1972 3,653,340

sum 1 OF 2 I E //2 WWW ROTARY TABLE SUMMARY OF THE INVENTION The presentinvention relates generally to free-wheeling rotary tables of the typeadapted to rotatably support an object, such as a workpiece or the likewhich is to have a manufacturing operation performed thereon. Suchoperations typically consist of various inspection, machining and/orassembly procedures which are performed in connection with theproduction of precision objects and equipment. More particularly, thepresent invention is directed toward a new and improved free-wheelingrotary table that utilizes a novel bearing structure which minimizesaxial runout and provides for extremely accurate concentricity withoutthe need for any precision, and thus expensive, bearing assemblies andmiscellaneous bearing keepers that have been required in similar typefree-wheeling rotary tables known in the prior art. The aforementionedbearing structure generally comprises an antifriction bearing assemblyconsisting of a plurality of ball bearing elements arranged coaxially ofthe rotational axis of the table and operatively engageable with abearing surface which is defined in part by a segment of imaginarysphere, the center of which lies along the rotational axis of the table.By virtue of the particular configuration of the bearing surface,accurate concentricity of rotation is achieved so that extremelyaccurate manufacturing and inspection operations may be performed uponthe objects, i.e., workpiece or the like, operatively disposed upon therotatable table member. Additionally, the particular design of theaforementioned bearing structure assures that the table is sufficientlyrugged, yet compact so that it may be relatively easily handled andtransported, yet will have a long and effective service life.

It is accordingly a general object of the present invention to provide anew and improved free-wheeling rotary table.

It is a more particular object of the present invention to provide a newand improved rotary table of the above described type which optimizesparallelism and concentricity and minimizes axial runout.

It is a further object of the present invention to provide a new andimproved free-wheeling rotary table which obviates the need forprecision and expensive bearing assemblies heretofore required insimilar type rotary tables.

It is yet another object of the present invention to provide a new andimproved rotary table which is of relatively simple design, iseconomical to manufacture, and easy to assemble.

Other objects and advantages of the present invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top elevational view of arotary table embodying the principles of the present invention;

FIG. 2 is a side elevational view of the rotary table illustrated inFIG. 1;

FIG. 3 is a transverse cross-sectional view of the rotary tableillustrated in FIGS. 1 and 2; and

FIG. 4 is an enlarged fragmentary view of a portion of the rotary tableillustrated in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in detailto the drawings and in particular to FIGS. 1 and 2, a free-wheelinghorizontal rotary table 10, in accordance with an exemplary embodimentof the present invention, is shown as generally comprising an annular orcircular, generally horizontally disposed support platform or tablemember 12 which is formed with a plurality of radially disposed,upwardly exposed inverted T-shaped slots 14. The slots 14 are adapted toreceive suitable screws, bolts, mounting brackets or the like fordetachably securing an object, such as a workpiece or the like, to theupper side of the table member 12 in a manner well known in the art. Thetable member 12 is operatively supported upon a table support or basemember, generally designated 16, which comprises a generally verticallydisposed annular side wall section 18 that extends downwardly below theouter marginal edge of the table member 12, as best seen in FIG. 3. Theside wall section 18 terminates at an integral lower support portion 20which, as seen in FIG. 1, is of a generally square configuration andcomprises four outwardly projecting mounting flange portions 22 that areformed with suitable threaded bores or the like 24 for receivingmounting screws, bolts or the like which function to secure the basemember 16, and hence the entire table 10, to a suitable supportstructure or the like (not shown). As will hereinafter be described indetail, the table member 12 is adapted to be operatively supported uponthe base member 16 in a manner such that the member 12 is free-wheeling,i.e., is freely manually rotatable, whereby objects or workpiecessupported on the upper surface of the table member 12 may be rotated tovarious positions about a generally vertically oriented rotational axisin order to have various manufacturing operations, i.e., machining,inspection, etc., performed thereon.

As best illustrated in FIG. 3, the base member 16 is formed with acentral, vertically disposed cylindrical support section 26 whichdefines a central cylindrical bore 28. The support section 26 isintegrally connected to the side wall section 18 by means of a generallyhorizontally disposed intermediate section 30, the lower side of whichmay be provided with a plurality of integral reinforcing web portions32, as illustrated. The upper side of the intermediate section 30 isfonned with an upwardly extending annular land or projection 34 whichprojects upwardly into a complementary-shaped upwardly extending annulargroove or recess 36 formed on the underside of the table member 12, theland 34 and groove 36 being out of contact with one another so as to beinterference-free and functioning to prevent the ingress of any dirt orthe like interiorly of the table 10 in a manner well known in the art.The upper side of the intermediate section 30 is also formed with anannular groove 38 spaced radially inwardly from the land 34 and adaptedto have a downwardly projecting annular land 40 that is formed on theunderside of the table 12 projecting interiorly thereof. The land 40 andgroove 38 function similar to the aforementioned land and groove 34 and36 and further cooperate with a locking assembly 42 which is adapted tolockingly secure the table member 12 in preselected rotational positionsrelative to the base member 16. The locking assembly 42 may be of anysuitable construction well known in the art and may, for example,comprise a suitable brake element 44 that is movable toward and awayfrom frictional engagement with the land 40 by means of a suitablecontrol knob or the like 46 that is accessible on the exterior of thetable 10, as illustrated.

The table member 12 is formed with a central annular opening 48 that isformed with a counterbore 50 within which an antifriction bearingassembly, generally designated 52, is mounted. The assembly 52 comprisesan annular cup-shaped bearing member or race 54 that is fabricated ofhardened steel and comprises a generally radially disposed lower section56 and an integral axially upwardly extending section 58. The assembly52 also comprises a plurality of ball-bearing elements, generallydesignated 60, which are arranged circumferentially around the bearingmember 54 and disposed in contact with the upper side of the section 56and radially inner side of the section 58 thereof. The bearing elements60 are operatively retained upon the member 54 by means of aconventional bearing keeper or the like, herein designated by thenumeral Extending axially through the opening 48 in the table member 12is a generally cylindrically shaped hub member 64 which defines acentral annular opening 66 and an exteriorly threaded lower end portion68. The hub member 64 extends downwardly through the opening 28 in thecentral support section 26 of the base member 16, and the upper endthereof extends axially upwardly to a position in generally axialalignment with the counterbore 50. The upper end of the hub member 64 isformed with a radially outwardly extending shoulder, generallydesignated 70, which comprises a bearing race and defines a bearingsurface 72 adapted for engagement with the bearing elements 60, as bestseen in FIG. 4. In accordance with the principles of the presentinvention, the bearing surface 72 lies along a segment of an imaginarysphere, herein shown in phantom lines and designated by the numeral 74,and having its center lying along the rotational axis of the tablemember 12 and located slightly above the upper surface thereof, asindicated at point C in the drawings. The segmental sphericalconfiguration of the surface 72 will be seen to optimize concentricityand parallelism of the table member 12, and at the same time, minimizeaxial runout without the need for any precision bearings as hasheretofore been required in similar type precision rotary tables.

The lower threaded end 68 of the hub member 64 extends downwardly belowthe lower end of the support section 26 of the base member 16 and isadapted to threadably receive a suitable retaining ring or the like 76which, when properly threadably advanced along the end portion 68,engages the lower side of the support section 26 to prevent relativeaxial movement between the hub member 64 and the base member 16 andassure positive engagement of the bearing surface 72 with the bearingelement 60. A suitable locking pin or the like 77 may be provided tolockingly secure the retaining ring 76 in a preselected position,whereby to prevent inadvertent rotation thereof, as will be apparent.

Disposed within the upper end of the opening 66 is a generallycylindrically shaped mounting spindle 78 which comprises a centralcylindrical body section 80 that extends downwardly within the upper endof the opening 66 and terminates at the upper end thereof at a generallyradially outwardly extending flange portion 82. The flange portion 82 isnestingly received within an annular counterbore or recess 83 formedaround the upper end of the counterbore 50 in a manner such that theupper surface of the flange portion 82 is flush, i.e., coplanar, withthe upper surface of the table member 12. Means in the form of suitablescrews, bolts or the like 84 are provided for fixedly securing theflange portion 82, and hence the spindle 78, to the table member 12,which screws 84 extend downwardly through counterbored openings 86 inthe flange portion 82 and are threadably received within suitableaxially and circumferentially aligned bores 88 in the table member 12.

In order to facilitate orientation of a workpiece or the like upon thetable member 12, said member 12 may be provided with a central upwardlyextending stub shaft 90, as illustrated in the drawings. The shaft 90 isshown as comprising a generally cylindrically shaped upper end portion92 which extends upwardly from the upper surface of the table member 12and is arranged coaxially of the rotational axis thereof. The shaft 90also comprises a downwardly and radially inwardly tapered lower endportion 94 which is adapted to be received within a suitablecomplementary-shaped, i.e., tapered, bore 96 in the mounting spindle 78.

Disposed approximately midway between the rotational axis of the tablemember 12 and the outer periphery thereof is an outer bearing assembly,generally designated by the numeral 98. The assembly 98 comprises a pairof generally ring-shaped or annular upper and lower bearing plates 100and 102, respectively, which are adapted to be fixedly secured to theunderside of the plate member 12 and the upper side of the intermediatesection 30 by means of suitable screws, bolts or the like 104 and 106,respectively. The bearing plates 100 and 102 are designed such that theconfronting surfaces thereof lie in vertically spaced, parallel planesand interposed therebetween is a plurality of circumferentially spacedantifriction ball-bearing elements, generally designated by the numeral108. The elements 108 are operatively retained at a position interjacentthe bearing plates 100, 102 by means of a suitable bearing keeper 110,as will be apparent to those skilled in the art. The outer bearingassembly 98 functions to support the outer peripheral portion of thetable member 12 when the same is subjected to extremely high loading,and it may be noted that in applications wherein high loading is notencountered, or wherein the objects to be supported upon the tablemember 12 have their weight concentrated about the center of the table10, the outer bearing assembly 98 may be omitted without departing fromthe scope of the present invention. Y

If desired, the rotational table 10 of the present invention may beprovided with a conventional slot pin assembly, herein designated by thenumeral 112, which is conventionally provided with a locking pin or thelike adapted to be moved into one of a series of circumferentiallyspaced bores provided in the underside of the table member 12 by meansof a suitable control knob or the like 114 and thereby lockingly securethe table member 12 in a preselected rotational position. In order toassist the operator in selectively rotatably positioning the tablemember 12 with respect to the base member 16, the members 12, 16 may beprovided with suitable locating indicia or the like 1 16, in a mannerwell known in the art.

While it will be apparent that the exemplary embodiment illustratedherein is well calculated to fulfill the objects above stated, it willbe appreciated that the present invention is susceptible tomodification, variation and change without departing from the scope ofthe invention.

What is claimed is:

l. A rotary workpiece support table comprising,

an annular base member having a central section and an,

outer peripheral support surface engaging section,

a horizontally disposed rotatable table member mounted on said basemember and adapted to support an object for rotation about a generallyvertical rotational axis,

said table member comprising a central section generally verticallyaligned with said central section of said base member and a generallyflat radially outwardly disposed section extending radially outwardly toa position overlying said outer peripheral section of said base member,

said central sections of said table member and said base member beingformed with vertically aligned bores arranged coaxially of saidrotational axis,

a generally cylindrically shaped hub member extending through saidbores,

an antifriction bearing assembly for rotatably supporting said tablemember on said base member and comprising a first bearing race on saidtable member, a second bearing race on said hub member, and a pluralityof antifriction ball bearing elements disposed between said first andsecond bearing races and lying along a common horizontally disposedplane,

one of said bearing races being defined in part by a segment of animaginary sphere having its center located on said axis of rotation anddisposed above said horizontal plane, whereby to optimize concentricityand parallelism and minimize axial runout of said table member relativeto said base member.

2. The combination as set forth in claim 1, which includes securingmeans engageable with the lower end of said hub member and adapted toexert an axially downwardly directed force thereagainst in order topositively engage said bearing elements with said bearing races.

3. The combination as set forth in claim 1 wherein said hub member isformed with a laterally outwardly directed shoulder at the upper endthereof, said shoulder comprising one of said bearing races and having abearing surface on the lower side thereof defined by said sector of saidimaginary sphere, the other of said bearing races being mounted on saidtable and being of a generally cup-shaped configuration and disposedbelow said shoulder for radially and axially confining said bearingelements.

4. The combination as set forth in claim 3 wherein said base member isformed with central sleeve section arranged coaxially of said rotationalaxis, wherein the lower end of said hub member extends downwardlythrough said sleeve section, and which includes a threadably mountedelement on the lower end of said hub member adapted to be tightenedagainst the I lower end of said sleeve section for asserting an axiallydownwardly directed force against the hub member.

5. The invention as set forth in claim 1 wherein the upper end of saidhub member includes a generally radially outwardly extending shoulderdefining a bearing surface on the radially outer and lower portionthereof, said surface being defined by said segment of said imaginarysphere.

6. The invention as set forth in claim 1 wherein the upper end'of saidcylindrical bore in said table member is formed with a counterbore, andwherein said antifriction bearing

1. A rotary workpiece support table comprising, an annular base memberhaving a central section and an outer peripheral support surfaceengaging section, a horizontally disposed rotatable table member mountedon said base member and adapted to support an object for rotation abouta generally vertical rotational axis, said table member comprising acentral section generally vertically aligned with said central sectionof said base member and a generally flat radially outwardly disposedsection extending radially outwardly to a position overlying said outerperipheral section of said base member, said central sections of saidtable member and said base member being formed with vertically alignedbores arranged coaxially of said rotational axis, a generallycylindrically shaped hub member extending through said bores, anantifriction bearing assembly for rotatably supporting said table memberon said base member and comprising a first bearing race on said tablemember, a second bearing race on said hub member, and a plurality ofantifriction ball bearing elements disposed between said first andsecond bearing races and lying along a common horizontally disposedplane, one of said bearing races being defined in part bY a segment ofan imaginary sphere having its center located on said axis of rotationand disposed above said horizontal plane, whereby to optimizeconcentricity and parallelism and minimize axial runout of said tablemember relative to said base member.
 2. The combination as set forth inclaim 1, which includes securing means engageable with the lower end ofsaid hub member and adapted to exert an axially downwardly directedforce thereagainst in order to positively engage said bearing elementswith said bearing races.
 3. The combination as set forth in claim 1wherein said hub member is formed with a laterally outwardly directedshoulder at the upper end thereof, said shoulder comprising one of saidbearing races and having a bearing surface on the lower side thereofdefined by said sector of said imaginary sphere, the other of saidbearing races being mounted on said table and being of a generallycup-shaped configuration and disposed below said shoulder for radiallyand axially confining said bearing elements.
 4. The combination as setforth in claim 3 wherein said base member is formed with central sleevesection arranged coaxially of said rotational axis, wherein the lowerend of said hub member extends downwardly through said sleeve section,and which includes a threadably mounted element on the lower end of saidhub member adapted to be tightened against the lower end of said sleevesection for asserting an axially downwardly directed force against thehub member.
 5. The invention as set forth in claim 1 wherein the upperend of said hub member includes a generally radially outwardly extendingshoulder defining a bearing surface on the radially outer and lowerportion thereof, said surface being defined by said segment of saidimaginary sphere.
 6. The invention as set forth in claim 1 wherein theupper end of said cylindrical bore in said table member is formed with acounterbore, and wherein said antifriction bearing means is disposed inpart within said counterbore.
 7. The invention as set forth in claim 1which includes second antifriction bearing means spaced radiallyoutwardly from said bearing assembly and interposed between theunderside of said table member and the upper side of said base member.8. The invention as set forth in claim 1 which includes spindle means onthe upper end of said hub member for centrally locating an object onsaid table member.